Arthur O. Lovejoy, The Great Chain Of Being: A Study of the History of an Idea (Cambridge, MASS: Harvard University Press, 1964; 1936), p. 7:
There are, first, implicit or incompletely explicit assumptions, or more or less unconscious mental habits, operating in the thought of an individual or a generation. It is the beliefs which are so much a matter of course that they are rather tacitly presupposed than formally expressed and argued for, the ways of thinking which seem so natural and inevitable that they are not scrutinized with the eye of logical self-consciousness, that often are most decisive of the character of a philosopher’s doctrine, and still oftener of the dominant intellectual tendencies of an age.